Bilingual children are often misdiagnosed as having a speech disorder when they truly exhibit normal development. In addition, speech-language pathologists (SLP) are avoiding the assessment of bilingual children due to the lack of knowledge and resources necessary for best practice with this population. Misdiagnosis of speech sound disorders in this population has long-term emotional, financial, and educational costs. Misdiagnosis of speech disorders in bilingual children can be prevented if we acquire more information on what constitutes normal and disordered speech development in the bilingual population. A theoretical model that allows us to differentiate difference in speech production (i.e., a difference in how a bilingual child speaks due to the influence of one language on the other) from speech disorder (i.e., an underlying speech-learning disability) will provide SLPs with the knowledge they need to prevent misdiagnosis. The Specific Aims of the proposed research are to (1) to develop a theoretical model that accounts for how between-language interaction facilitates or inhibits speech sound production in bilinguals by measuring how, and to what extent, the two languages of bilinguals interact and (2) develop evidence based diagnostic criteria for clinicians to differentiate typically- developing bilingual children rom bilingual children with speech sound disorders. Bilingual children with typical and disordered development will be compared to their English-speaking peers on measures of speech sound ability. Children will produce sounds in single words and their productions will be phonetically transcribed. Child productions will be examined, in both English and Spanish and across both languages, on common diagnostic measures used for monolingual children. Mixed effects regression models will be used to identify between- language interaction in bilingual speech and the Receiver Operating Characteristic Curve (ROC) will be used to determine sensitivity and specificity of the diagnostic measures examined. Findings will lead to a characterization of typical and disordered speech sound development in bilingual children and diagnostic guidelines for speech-language pathologists to use in the differential diagnosis of speech difference from speech disorder. These findings will reduce diagnostic error in the identification of speech sound disorders in this population, reducing health disparities for Latino children.